This invention relates generally to honeycomb structures and in particular, structures having a honeycomb core in combination with a skin material. An example of such structures are certain aircraft structures such as helicopter rotor blades. Helicopter rotor blades, depending upon the particular design, may have tip and root sections which must be sealed. Such sealing is required in order to prevent moisture from entering and propagating into the structure and causing a deterioration of the bonding materials which connect the skin to the honeycomb core. Sealing is accomplished, in part, by bonding an end closure to the exposed honeycomb face. The enclosure, which may be an elastomeric closure or a molded elastomeric end closure, generally wraps around and is also bonded to the skin. This problem is particularly severe in aircraft structures due to the wide range of temperatures and pressures encountered during operational use.